"The partnership is an improvement but no silver bullet to Qantas's ails," said leading industry watchdog the Centre for Aviation.

"It will help Qantas's footprint in Europe but has little direct impact on Qantas's loss-making position in Asia."

Subject to regulatory approval, the deal goes beyond codesharing to include coordinated pricing, sales and scheduling and a benefit-sharing model, although neither airline will take equity in the other.

It also means an end to Qantas's partnership with British Airways on the so-called kangaroo route to London, which has spanned nearly two decades.

"It is far bigger than a codeshare or even a joint services agreement. This is the biggest arrangement Qantas has ever entered into with another airline."

Under the deal, Qantas will fly daily A380 services from both Sydney and Melbourne to London via Dubai, meaning that between the two airlines there will be 98 weekly services between Australia and the Emirates hub.

It will see Qantas become the only other airline operating to Terminal 3 and the new purpose-built A380 concourse at Dubai International Airport.

As a consequence, Qantas flights to Singapore and Hong Kong will terminate in those countries and be rescheduled to enable more same-day connections across Asia.

For Emirates customers, the alliance will open up Qantas's Australian domestic network of more than 50 destinations and nearly 5,000 flights per week.

"This is a momentous day in international aviation and it's exciting to be part of," said Emirates chief Tim Clark.

"The time was right to develop a long-term partnership with Qantas, the iconic Australian airline.

"By establishing this partnership we are providing our passengers with additional connectivity in Australia and the region, the ability to utilise reciprocal frequent flyer benefits and access to premium lounges and travel experiences."

The arrangement, which requires approval from Australian regulators, is expected to start in April 2013 and is seen as pivotal to the future of Qantas.

The Australian carrier makes good money on its domestic routes but has been dragged down by its loss-making international operations.

While the Centre for Aviation were cautious, Macquarie Equities analyst Russell Shaw called the deal the "missing piece in the earnings bridge" to help turn around the airline's fortunes.

Last month, Qantas announced a net loss of Aus$244 million (US$248 million), with its international arm accounting for much of the half-billion-dollar reverse from the previous 12 months.

Joyce said the tie-up would help repair Qantas International, which has been facing intense competition and soaring fuel costs.

"A key objective is to make Qantas International strong and viable, and bring it back to profitability," he said.

"This partnership will help us do that, while building on our strengths in Qantas domestic, Qantas Frequent Flyer and (low-cost carrier) Jetstar."